Make URL to the privacy policy configurable

[brknkfr]

We don't want to link to GitHub with our self-hosted Altbot by accepting the privacy policy because of privacy reasons. Unfortunately in most clients the URL to the privacy policy is rendered and in this case data is submitted to GitHub.

And the hard coded URL to the privacy policy is used in

Altbot/gdpr_consent.go

Line 328 in 291af24

if !containsWord(stripHTMLTags(parentStatus.Content), "https://github.com/micr0-dev/Altbot/blob/main/PRIVACY.md") {

which makes it more difficult to use a custom privacy policy with a self-hosted Altbot.

This would probably need changes in the localizations.json file as well.